Sustained-release nifedipine (nifedipine-L) suppresses plasma thromboxane B2 and 6-keto prostaglandin F1α in both young male smokers and nonsmokers

Sustained-release nifedipine (nifedipine-L) (40 mg twice a day) was administered orally to healthy young adult male smokers and nonsmokers for 10 days, and its effects on platelet aggregation, β -thromboglobulin and platelet factor 4 levels, and plasma thromboxane B 2 (TxB 2 ) and 6-ketoprostaglandin F 1 α (6-Keto-PGF 1 α ) concentrations were studied. The plasma nifedipine-L concentration in smokers (46.0±7.4 ng/ml) was significantly lower than that in nonsmokers (88.2±1.2 ng/ml). Nifedipine-L did not affect platelet aggregation induced by adenosine diphosphate, collagen, or epinephrine in either smokers or nonsmokers. The plasma β -thromboglobulin level on the tenth day of nifedipine-L administration in nonsmokers was lower than that in smokers, but there were no significant differences either with or without nifedipine-L or between nonsmokers and smokers. Nifedipine-L had no effect on the concentration of platelet factor 4 in either smokers or nonsmokers. On the other hand, nifedipine-L significantly decreased the plasma TxB 2 and 6-keto-PGF 1 α concentrations in both smokers and nonsmokers. Thus we concluded that nifedipine-L suppressed the production of plasma TxB 2 from platelets and also subsequently suppressed the production of 6-keto-PGF 1 α and that this action was not affected by cigarette smoking.